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btrfs: move root node locking helpers to locking.c 

The helpers are related to locking so move them there, update comments.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2020-02-05 17:26:51 +01:00
parent 0024652895
commit b908c334e7
2 changed files with 42 additions and 38 deletions
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38
fs/btrfs/ctree.c
View File

@ -143,44 +143,6 @@ struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
return eb;
}
/* loop around taking references on and locking the root node of the
* tree until you end up with a lock on the root. A locked buffer
* is returned, with a reference held.
*/
struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
{
struct extent_buffer *eb;
while (1) {
eb = btrfs_root_node(root);
btrfs_tree_lock(eb);
if (eb == root->node)
break;
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
}
return eb;
}
/* loop around taking references on and locking the root node of the
* tree until you end up with a lock on the root. A locked buffer
* is returned, with a reference held.
*/
struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
{
struct extent_buffer *eb;
while (1) {
eb = btrfs_root_node(root);
btrfs_tree_read_lock(eb);
if (eb == root->node)
break;
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
}
return eb;
}
/* cowonly root (everything not a reference counted cow subvolume), just get
* put onto a simple dirty list. transaction.c walks this to make sure they
* get properly updated on disk.

42
fs/btrfs/locking.c
View File

@ -523,3 +523,45 @@ void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
path->locks[i] = 0;
}
}
/*
* Loop around taking references on and locking the root node of the tree until
* we end up with a lock on the root node.
*
* Return: root extent buffer with write lock held
*/
struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
{
struct extent_buffer *eb;
while (1) {
eb = btrfs_root_node(root);
btrfs_tree_lock(eb);
if (eb == root->node)
break;
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
}
return eb;
}
/*
* Loop around taking references on and locking the root node of the tree until
* we end up with a lock on the root node.
*
* Return: root extent buffer with read lock held
*/
struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
{
struct extent_buffer *eb;
while (1) {
eb = btrfs_root_node(root);
btrfs_tree_read_lock(eb);
if (eb == root->node)
break;
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
}
return eb;
}